Power Transistor Abnormality Detection Circuit
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Solution Overview
Problem
Conventional abnormality detection apparatuses for power feed circuits fail to quickly detect open-circuit and short-circuit abnormalities, leading to inadequate protection of power transistors, as they do not effectively handle overcurrent limiting and transition characteristics of abnormal states.
Innovation Solution
An abnormality detection apparatus with a single state detection circuit that includes a constant current control circuit, an overheat interruption circuit, and a state detection circuit, which uses a switching control section to determine and respond to short-circuit and open-circuit abnormalities by maintaining a stable voltage across the power transistor and preventing overcurrent stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional abnormality detection apparatuses are used, then the power transistor can operate with basic overcurrent limiting, but open-circuit and short-circuit abnormalities cannot be detected quickly, leading to inadequate protection
Solution Approach 1:
The patent applies preliminary action by performing abnormality detection during the transition period when the power transistor is switching off. The detection circuit monitors the voltage across the power transistor during this critical transition phase, allowing abnormality detection to occur before the abnormal state can cause damage, rather than waiting for the abnormality to manifest during steady-state operation.
Solution Approach 2:
The patent implements feedback by continuously monitoring the voltage across the power transistor during switching transitions and using this information to detect abnormalities. The detection circuit provides real-time feedback about the state of the power transistor, enabling quick identification of open-circuit or short-circuit conditions and allowing the control system to respond appropriately to protect the transistor.
2Measurement precision
If artificial energization methods are used for detection, then abnormalities can be detected, but the detection cannot account for overcurrent limiting characteristics and transition characteristics, resulting in slow detection speed
Solution Approach 1:
The patent applies dynamics by detecting abnormalities during the dynamic transition period of the power transistor switching operation, rather than during static steady-state periods. The detection circuit monitors voltage changes as the transistor transitions from on to off state, capturing abnormal conditions while the system is in a dynamic state, which provides both speed and accuracy in detection.
Solution Approach 2:
The patent utilizes parameter changes by monitoring voltage across the power transistor during the switching transition when electrical parameters are changing rapidly. The detection circuit identifies abnormalities by analyzing voltage characteristics during this dynamic parameter change period, enabling fast detection that accounts for the actual operating conditions including overcurrent limiting characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables quick detection of open-circuit and short-circuit states, reducing overcurrent stress on power transistors and preventing burnout by stabilizing voltage and controlling current flow, thus enhancing the protection of power transistors.
Implementation Method 1
The comparison control circuit includes a temperature detection element for detecting a temperature in the vicinity of the power transistor
Implementation Method 2
The constant current control circuit includes a conduction control transistor that operates in response to a detected voltage of a current detection resistor
Data Source
AI summary
A single state detector circuit can quickly detect short-circuit and open-circuit abnormalities of a load controlled by a power transistor. A DC power supply, the load and the power transistor are serially connected with one another, so that a switching terminal voltage of the power transistor is binarized into high and low levels by the state detector. The power transistor is linearly controlled by a constant-current control circuit so as to suppress an excessive current, and power supplied to the power transistor is interrupted by an overheat interruption circuit. Upon occurrence of a short-circuit in the load during generation of an energization command, a switching terminal voltage of the power transistor becomes stabilized at a high level without intermittent operation, which is detected by the state detector. Upon occurrence of an open-circuit during generation of a deenergization command, a low switching terminal voltage is detected by the state detector.